!899 Optimize dladdr performance

Merge pull request !899 from yinchuang/opt_dladdr

porting/linux/user/ldso/dynlink.c

@@ -105,7 +105,7 @@ struct reserved_address_params {
 #endif
 };
 
-typedef void (*stage3_func)(size_t *, size_t *);
+typedef void (*stage3_func)(size_t *, size_t *, size_t *);
 
 static struct builtin_tls {
 	char c[8];
@@ -2609,6 +2609,9 @@ hidden void __dls2(unsigned char *base, size_t *sp)
 	} else {
 		ldso.base = base;
 	}
+	size_t aux[AUX_CNT];
+	decode_vec(auxv, aux, AUX_CNT);
+	libc.page_size = aux[AT_PAGESZ];
 	Ehdr *ehdr = (void *)ldso.base;
 	ldso.name = ldso.shortname = "libc.so";
 	ldso.phnum = ehdr->e_phnum;
@@ -2645,8 +2648,8 @@ hidden void __dls2(unsigned char *base, size_t *sp)
 	 * symbolically as a barrier against moving the address
 	 * load across the above relocation processing. */
 	struct symdef dls2b_def = find_sym(&ldso, "__dls2b", 0);
-	if (DL_FDPIC) ((stage3_func)&ldso.funcdescs[dls2b_def.sym-ldso.syms])(sp, auxv);
-	else ((stage3_func)laddr(&ldso, dls2b_def.sym->st_value))(sp, auxv);
+	if (DL_FDPIC) ((stage3_func)&ldso.funcdescs[dls2b_def.sym-ldso.syms])(sp, auxv, aux);
+	else ((stage3_func)laddr(&ldso, dls2b_def.sym->st_value))(sp, auxv, aux);
 }
 
 /* Stage 2b sets up a valid thread pointer, which requires relocations
@@ -2655,7 +2658,7 @@ hidden void __dls2(unsigned char *base, size_t *sp)
  * so that loads of the thread pointer and &errno can be pure/const and
  * thereby hoistable. */
 
-void __dls2b(size_t *sp, size_t *auxv)
+void __dls2b(size_t *sp, size_t *auxv, size_t *aux)
 {
 	/* Setup early thread pointer in builtin_tls for ldso/libc itself to
 	 * use during dynamic linking. If possible it will also serve as the
@@ -2669,8 +2672,8 @@ void __dls2b(size_t *sp, size_t *auxv)
 	}
 
 	struct symdef dls3_def = find_sym(&ldso, "__dls3", 0);
-	if (DL_FDPIC) ((stage3_func)&ldso.funcdescs[dls3_def.sym-ldso.syms])(sp, auxv);
-	else ((stage3_func)laddr(&ldso, dls3_def.sym->st_value))(sp, auxv);
+	if (DL_FDPIC) ((stage3_func)&ldso.funcdescs[dls3_def.sym-ldso.syms])(sp, auxv, aux);
+	else ((stage3_func)laddr(&ldso, dls3_def.sym->st_value))(sp, auxv, aux);
 }
 
 /* Stage 3 of the dynamic linker is called with the dynamic linker/libc
@@ -2678,10 +2681,9 @@ void __dls2b(size_t *sp, size_t *auxv)
  * process dependencies and relocations for the main application and
  * transfer control to its entry point. */
 
-void __dls3(size_t *sp, size_t *auxv)
+void __dls3(size_t *sp, size_t *auxv, size_t *aux)
 {
 	static struct dso app, vdso;
-	size_t aux[AUX_CNT];
 	size_t i;
 	char *env_preload=0;
 	char *replace_argv0=0;
@@ -2694,10 +2696,8 @@ void __dls3(size_t *sp, size_t *auxv)
 	/* Find aux vector just past environ[] and use it to initialize
 	 * global data that may be needed before we can make syscalls. */
 	__environ = envp;
-	decode_vec(auxv, aux, AUX_CNT);
 	search_vec(auxv, &__sysinfo, AT_SYSINFO);
 	__pthread_self()->sysinfo = __sysinfo;
-	libc.page_size = aux[AT_PAGESZ];
 	libc.secure = ((aux[0]&0x7800)!=0x7800 || aux[AT_UID]!=aux[AT_EUID]
 		|| aux[AT_GID]!=aux[AT_EGID] || aux[AT_SECURE]);
 
@@ -3511,31 +3511,19 @@ void *addr2dso(size_t a)
 {
 	struct dso *p;
 	size_t i;
-	if (DL_FDPIC) for (p=head; p; p=p->next) {
-		i = count_syms(p);
-		if (a-(size_t)p->funcdescs < i*sizeof(*p->funcdescs))
-			return p;
-	}
 	for (p=head; p; p=p->next) {
-		if (DL_FDPIC && p->loadmap) {
-			for (i=0; i<p->loadmap->nsegs; i++) {
-				if (a-p->loadmap->segs[i].p_vaddr
-					< p->loadmap->segs[i].p_memsz)
-					return p;
-			}
-		} else {
-			Phdr *ph = p->phdr;
-			size_t phcnt = p->phnum;
-			size_t entsz = p->phentsize;
-			size_t base = (size_t)p->base;
-			for (; phcnt--; ph=(void *)((char *)ph+entsz)) {
-				if (ph->p_type != PT_LOAD) continue;
-				if (a-base-ph->p_vaddr < ph->p_memsz)
-					return p;
-			}
-			if (a-(size_t)p->map < p->map_len)
-				return 0;
+		if (a < p->map || a - (size_t)p->map >= p->map_len) continue;
+		Phdr *ph = p->phdr;
+		size_t phcnt = p->phnum;
+		size_t entsz = p->phentsize;
+		size_t base = (size_t)p->base;
+		for (; phcnt--; ph=(void *)((char *)ph+entsz)) {
+			if (ph->p_type != PT_LOAD) continue;
+			if (a-base-ph->p_vaddr < ph->p_memsz)
+				return p;
 		}
+		if (a-(size_t)p->map < p->map_len)
+			return 0;
 	}
 	return 0;
 }
@@ -3777,15 +3765,71 @@ hidden int __dlclose(void *p)
 	return rc;
 }
 
+static inline int sym_is_matched(const Sym* sym, size_t addr_offset_so) {
+	return sym->st_value &&
+		(1<<(sym->st_info&0xf) != STT_TLS) &&
+		(addr_offset_so >= sym->st_value) &&
+		(addr_offset_so < sym->st_value + sym->st_size);
+}
+
+static inline Sym* find_addr_by_elf(size_t addr_offset_so, struct dso *p) {
+	uint32_t nsym = p->hashtab[1];
+	Sym *sym = p->syms;
+	for (; nsym; nsym--, sym++) {
+		if (sym_is_matched(sym, addr_offset_so)) {
+			return sym;
+		}
+	}
+
+	return NULL;
+}
+
+static inline Sym* find_addr_by_gnu(size_t addr_offset_so, struct dso *p) {
+
+	size_t i, nsym, first_hash_sym_index;
+	uint32_t *hashval;
+	Sym *sym_tab = p->syms;
+	uint32_t *buckets= p->ghashtab + 4 + (p->ghashtab[2]*sizeof(size_t)/4);
+	// Points to the first defined symbol, all symbols before it are undefined.
+	first_hash_sym_index = buckets[0];
+	Sym *sym = &sym_tab[first_hash_sym_index];
+
+	// Get the location pointed by the last bucket.
+	for (i = nsym = 0; i < p->ghashtab[0]; i++) {
+		if (buckets[i] > nsym)
+			nsym = buckets[i];
+	}
+
+	for (i = first_hash_sym_index; i < nsym; i++) {
+		if (sym_is_matched(sym, addr_offset_so)) {
+			return sym;
+		}
+		sym++;
+	}
+
+	// Start traversing the hash list from the position pointed to by the last bucket.
+	if (nsym) {
+		hashval = buckets + p->ghashtab[0] + (nsym - p->ghashtab[1]);
+		do {
+			nsym++;
+			if (sym_is_matched(sym, addr_offset_so)) {
+				return sym;
+			}
+			sym++;
+		}
+		while (!(*hashval++ & 1));
+	}
+
+	return NULL;
+}
+
+
 int dladdr(const void *addr_arg, Dl_info *info)
 {
 	size_t addr = (size_t)addr_arg;
 	struct dso *p;
-	Sym *sym, *bestsym;
-	uint32_t nsym;
+	Sym *match_sym = NULL;
 	char *strings;
-	size_t best = 0;
-	size_t besterr = -1;
 
 	pthread_rwlock_rdlock(&lock);
 	p = addr2dso(addr);
@@ -3793,54 +3837,26 @@ int dladdr(const void *addr_arg, Dl_info *info)
 
 	if (!p) return 0;
 
-	sym = p->syms;
 	strings = p->strings;
-	nsym = count_syms(p);
+	size_t addr_offset_so = addr - (size_t)p->base;
 
-	if (DL_FDPIC) {
-		size_t idx = (addr-(size_t)p->funcdescs)
-			/ sizeof(*p->funcdescs);
-		if (idx < nsym && (sym[idx].st_info&0xf) == STT_FUNC) {
-			best = (size_t)(p->funcdescs + idx);
-			bestsym = sym + idx;
-			besterr = 0;
-		}
-	}
+	info->dli_fname = p->name;
+	info->dli_fbase = p->map;
 
-	if (!best) for (; nsym; nsym--, sym++) {
-		if (sym->st_value
-		 && (1<<(sym->st_info&0xf) & OK_TYPES)
-		 && (1<<(sym->st_info>>4) & OK_BINDS)) {
-			size_t symaddr = (size_t)laddr(p, sym->st_value);
-			if (symaddr > addr || symaddr <= best)
-				continue;
-			best = symaddr;
-			bestsym = sym;
-			besterr = addr - symaddr;
-			if (addr == symaddr)
-				break;
-		}
-	}
+	if (p->ghashtab) {
+		match_sym = find_addr_by_gnu(addr_offset_so, p);
 
-	if (best && besterr > bestsym->st_size-1) {
-		best = 0;
-		bestsym = 0;
+	} else {
+		match_sym = find_addr_by_elf(addr_offset_so, p);
 	}
 
-	info->dli_fname = p->name;
-	info->dli_fbase = p->map;
-
-	if (!best) {
+	if (!match_sym) {
 		info->dli_sname = 0;
 		info->dli_saddr = 0;
 		return 1;
 	}
-
-	if (DL_FDPIC && (bestsym->st_info&0xf) == STT_FUNC)
-		best = (size_t)(p->funcdescs + (bestsym - p->syms));
-	info->dli_sname = strings + bestsym->st_name;
-	info->dli_saddr = (void *)best;
-
+	info->dli_sname = strings + match_sym->st_name;
+	info->dli_saddr = (void *)laddr(p, match_sym->st_value);
 	return 1;
 }